The present invention disclosed herein relates to thermoelectric devices, and more particularly, to thermoelectric devices based on semiconductor processes and methods for fabricating the same.
Thermoelectric devices convert thermal energy into electrical energy. Recently, thermoelectric devices are receiving much attention due to clean energy-oriented policy. A thermoelectric effect was discovered in 1800's by Thomas Seebeck. Thomas Seebeck connected bismuth and copper and disposed a compass therein. When one side of the bismuth is heated to high temperature, a current is induced due to a temperature difference. A magnetic field created by the induced current moves a needle of the compass, thereby discovering the thermoelectric effect.
A value of Figure of Merit (ZT) is used as an index of thermoelectric efficiency. The ZT value is proportional to the electric conductivity and the square of a Seebeck coefficient. The ZT value is inversely proportional to the thermal conductivity. Metal has a low Seebeck coefficient and its electric conductivity is proportional to its thermal conductivity according to Wiedemann-Franz law. Thus, metal has a limitation in increasing the ZT value. Bi2Te3 is widely used as thermoelectric material. However, thermoelectric devices based on Bi2Te3 use heavy metals and are difficult to reuse. Also, the thermoelectric devices based on Bi2Te3 are low in mechanical strength, difficult to miniaturize, and weak to moisture.